1. Field of the Invention (Technical Field)
The present invention relates to medical equipment and methods, more particularly to equipment and methods for radiation therapy including stereotactic localization and immobilization systems and methods.
2. Background Art
Fractionated radiation therapy to a target lesion within the body is the primary method used for radiation therapy. This method requires precise immobilization and repositioning of the patient for other treatment sessions. Stereotactic localization and procedures on cranial and extra-cranial body parts have a similar requirement.
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
The need for effective patient immobilization techniques for radiation therapy has recently inspired the development and use of many immobilization devices in that field. The ability to reposition the patient and the patient""s ability to maintain the position during treatment may be improved with the use of immobilization devices (see Bentel 1999). Immobilization reduces xe2x80x9cnormal tissuexe2x80x9d complication rate, allows increased irradiation, and improves tumor control rate. xe2x80x9cA modest increase of the treatment and isodose margin can have a significant effect on the volume of normal tissue exposedxe2x80x9d (see Bentel 1999). Historically, skin marks, or marker systems (see U.S. Pat. No. 4,583,538, to Onik, et al.), have been used to aid in target localization and repositioning. Skin marks used for patient repositioning may migrate as they are re-marked and markings can shift with respect to underlying deeper tissues. They also tend to smear and fade. Markings on a body immobilization device do not move with respect to the target, they do not smear or fade, hence the problems of re-marking and migration are eliminated (see Bentel 1999). Markings on the immobilization device may also be matched to skin markings (see Bentel 1999).
Patient comfort, ability to easily maintain the position for extended periods of time, reproducibility of the patient""s xe2x80x9cprescriptionxe2x80x9d position, and anticipated beam orientation are essential in successful repeat radiotherapy treatments (see Bentel 1999). Comfort allows the patient to relax in a position throughout the treatment period, discouraging body movement caused by fatigue or discomfort. Patient movement could invalidate target localization and expose healthy tissue to unwanted radiation. Some patients, especially children, may move as much as 5 mm (or more) during treatment (due to pain or an uncomfortable position or because they are uncooperative, demented or restless) (see Bentel 1999). Goitein and Busse studied the theoretical effect of under dosage at the perimeter of the treatment field caused by random immobilization errors. They found that as much as a 12% improvement of tumor control probability could be achieved by good Immobilization techniques (see Bentel 1999). In addition, a cost reduction is realized over traditional radiation therapy because the number of port films as well as setup time is reduced which allows for more patient throughput (see Bentel 1999).
Because body fixation is essential for controlled radiation therapy during cancer treatment (Lederman, et al. 1998), emphasis has been placed on non-invasive and comfortable means of body immobilization and repositioning (see Bentel 1999). New techniques for precision radiation to extracranial targets of the body have been developed for highly successful treatment of lesions. External fixation systems are used to localize the body for exact repositioning during repeat treatments. The concept of stereotactic localization has been used to localize and aid in the target positioning for radiotherapy (see Lax, et al. 1994 and Hamilton, et al 1995).
Bentel (Bentel 1999) references a concept of three-dimensional localization (stereotactic localization) when she states that xe2x80x9cThe coordinate system allows one to describe the location of any point with respect to another known point (origin). Three axes (x,y,z) transect this known point. The location of any point with respect to the origin is described by the distance measured along each axis and by indicating on which side of the axis the point is located.xe2x80x9d These concepts are fundamental to the principles of stereotactc localization, which is to determine the location of deep body structures which are invisible from the surface but their location can be determined by a knowledge of their three-dimensional coordinates in space relative to known anatomical and topographical landmarks in a volumetric space defined by a stereotactic instrument. The stereotactic technique seeks to avoid disturbance to surrounding structures during therapeutic interventions by the use of minimally invasive precision localization Instruments. Guiot, G. and Derome, P., xe2x80x9cThe principles of stereotactic thalamotomyxe2x80x9d, Correlative Neurosurgery, edited by Kahn, E J et al., Springfield, Ill., 2nd Edition, Chapter 18, pp. 376-401, 1969.
As noted by Bentel and Marks (Bentel, et al. 1997) and Bentel (Bentel 1999), a number of methods have been historically used for patient immobilization during radiation therapy. More recently the concept of stereotactic localization, which has previously been successfully applied to radiotherapy/radiosurgery of the brain (see Lutz, et al. 1988), has been applied to extracranial radiotherapy target areas. (Lax 1994, Lederman 1998, and Hamilton, et al., 1995 and 1997).
This method of patient immobilization and stereotactic localization has been found to be more effective than previous localization methods for radiation therapy. Lax, et al. (Lax, et al. 1994), found a high degree of target reproducibility when using a stereotactic body frame. They found, from repeat CT examinations of patients in the body frame, a 5 mm range (i.e., a 2-7 mm range of error) of target volume positioning for targets in the liver and lungs. In addition, local tumor control of 90% was possible using this technique (see Blomgren, et al. 1995). The clinical use of a stereotactic body frame is increasing because it can be used to treat lesions over a wide variety of body areas (see Lederman, et al. 1998a-g).
Additional references providing important background to the present invention include the following U.S. Pat. No. 3,783,251, to Pavkovich, et al.; U.S. Pat. No. 4,583,538, to Onik, et al.; U.S. Pat. No. 4,638,798, to Shelden, et al.; U.S. Pat. No. 4,341,220, to Perry; U.S. Pat. No. 4,608,977, to Brown, et al.; U.S. Pat. No. 4,618,978, to Cosman, et al.; U.S. Pat. No. 5,099,846, to Hardy, U.S. Pat. No. 5,553,112, to Hardy, et al.; U.S. Pat. No. 5,143,076, to Hardy, et al.; U.S. Pat. No. 5,176,689, to Hardy, et al.; U.S. Pat. No. 5,398,684, to Hardy, et al.; U.S. Pat. No. 5,354,314, to Hardy, et al.; and U.S. Pat. No. 6,011,828, to Hardy, et al. Other background publication include: Bentel, G. C., xe2x80x9cCentral Nervous System,xe2x80x9d Patient Positioning and Immobilization in Radiation Oncology, New York: McGraw-Hill, 1999, pp. 71-92; Bentel, G. C., xe2x80x9cGeneral Consideration of Positioning and Immobilization,xe2x80x9d Patient Positioning and Immobilization in Radiation Oncology, New York: McGraw-Hill, 1999, pp. 23-38; Bentel, G. C., xe2x80x9cTreatment Accuracy and Precision,xe2x80x9d Patient Positioning and Immobilization in Radiation Oncology, New York: McGraw-Hill, 1999, pp. 11-22; Bentel, G. C., xe2x80x9cTreatment Geometry,xe2x80x9d Patient Positioning and Immobilization in Radiation Oncology, New York: McGraw-Hill, 1999, pp. 1-10; Bertolina, J. A., et al., xe2x80x9cQuality Assurance Testing for An Extracranial Stereotactic Device: Methods and Results,xe2x80x9d Poster No. 129, Intl Stereotactic Radiosurgery Society, 1997, p. 233; Blomgren, H., et al., xe2x80x9cRadiosurgery for Tumors in the Body: Clinical Experience Using a New Method,xe2x80x9d J. of Radiosurgery, Vol. 1:1, pp. 63-74, 1998; Ferrero, R., xe2x80x9cConsider using resolver and synchros,xe2x80x9d Electronic Design, Vol. 17, 1975; Goldberg, A., et al., xe2x80x9cHypofractionated Body Radiosurgery (HBR) As Treatment Of Primary Pancreas Cancers,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/Hypocancer, 1998; Hanselman, D., xe2x80x9cResolver Signal Requirements for High Accuracy Resolver-to-Digital Conversion,xe2x80x9d IEEE Transactions on Industrial Electronics, Vol. 37, No. 6, pp. 556-561, 1990, Hamilton, A. J. , xe2x80x9cLINAC-Based Spinal Stereotactic Radiosurgery,xe2x80x9d 1995 Quadrennial Meeting of the American Society for Stereotactic and Functional Neurosurgery, 1995, p. 69; Hamilton, A. J., et al., Paper No. 49xe2x80x94xe2x80x9cPhase I Prototype Device for Spinal Stereotactic Radiosurgery,xe2x80x9d Intl Stereotactic Radiosurgery Society, 3rd Congress, 1997a, p. 83; Hamilton, A. J., et al., Paper No. 29xe2x80x94xe2x80x9cSpinal Stereotactic Radiosurgery: A Viable Treatment Strategy for Spinal Neoplasms Failing Standard Fractionated Radiotherapy,xe2x80x9d Intl Stereotactic Radiosurgery Society, 1997b, p. 55; Hamilton, A. J., xe2x80x9cLinear Accelerator (LINAC)-Based Stereotactic Spinal Radiosurgery,xe2x80x9d in Gildenberg, P. L. et al., eds, Textbook of Stereotactic and Functional Neurosurgery, New York: McGraw-Hill, 1998, pp. 857-869; Herfath, K. K., et al., xe2x80x9cExtracranial Stereotactic Conformal Radiation (3 Treatment of Tumors in the Liver and the Lung,xe2x80x9d I.J. Radiation Oncology Bio Phys, Vol. 42:1, p. 214, Supplement 1998; Lattanzi, J. P., et al., xe2x80x9cA Comparison of Daily CT Localization To A Daily Ultrasound Based System (BAT(trademark)) In Prostate Carcinoma. Will BAT Fly?xe2x80x9d, I.J. Radiation Oncology Bio Phys, Vol. 42:1, p. 215, Supplement 1998; Lax I., et al., xe2x80x9cStereotactic Radiotherapy Of Malignancies In The Abdomenxe2x80x94Methodological aspects,xe2x80x9d Acta Oncologica, 33:677-683, 1994; Lax, I., et al., xe2x80x9cStereotactic Radiotherapy Of Extracranial Targets,xe2x80x9d Med. Phys, pp. 112-113, 1994; Lax, I., et al., xe2x80x9cExtracranial Stereotactic Radiosurgery of Localized Targets,xe2x80x9d J. Of Radiosurgery, Vol.1:2, pp. 135148, 1998; Lederman, G. et al., eds: xe2x80x9cBody Radiosurgery Resultsxe2x80x9d, J. of Radiosurgery, www.siuh.edu.radoncology/bradresults, 1998a; Lederman, G. et al., eds: xe2x80x9cBody Radiosurgery Treatment Procedure,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/bradprocedure, 1998b; Lederman, G. et al., eds: xe2x80x9cFractionated Stereotactic Body Radiosurgery at Staten Island University Hospital,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/bodyrs, 1998c; Lederman, G. et al., eds: xe2x80x9cInnovative Treatment For Pancreas Cancers,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/pancancer, 1998d; Lederman, G. et al., eds: xe2x80x9cFractionated Stereotactic Body Radiosurgery, An Innovative and Effective New Treatment Method,xe2x80x9d J. of Radiosurgery, www.siuh.edu/radoncology/bodyrad, 1998e; Lederman, G., et al., xe2x80x9cBody Stereotactic Radiosurgery (BSR) For Extracranial Metastases,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/Extracran, 1998f; Lederman, G., et al., xe2x80x9cBody Stereotactic Radiosurgery (BSR) For Primary Extracranial Tumors,xe2x80x9d J. of Radiosurgery, www.siuh.edu.radoncology/extracrantumor, 1998g; Sato, M., et al., xe2x80x9cFeasibility of Frameless Stereotactic High-Dose Radiation Therapy for Primary or Metastatic Liver Cancer,xe2x80x9d J. of Radiosurgery, Vol. 1:3, pp. 233-238, 1998; Stea, B., et al., xe2x80x9cSpinal Stereotactic Radiosurgery: A :Phase-I Study,xe2x80x9d I.J. Radiation Oncology Bio Phys, Vol. 42:1, p. 214, Supplement 1998; Onik, G., et al., xe2x80x9cCT Body Stereotactic System for Placement of Needle Arrays,xe2x80x9d Int. J. Radiation Oncology Biol. Phys., Vol. 13, pp. 121-128, 1987; Wulf, J., et al., xe2x80x9cHypofractionated, High-dose Radiation Under Stereotactic Conditions in the Stereotactic Body Frame: Accuracy of Re-positioning At 11 CT-Simulations And 37 Applications At The LINAC,xe2x80x9d I.J. Radiation Oncology Bio Phys, Vol. 42:1 p. 215, Supplement 1998; Lutz, W., et al., xe2x80x9cA System of Stereotactic Radiosurgery with a Linear Accelerator,xe2x80x9d Int""l J. Radiation Oncology and Biological Physics, Vol. 14, pp. 37381 (1988); Hardy, T. L., et al., xe2x80x9cCASS: A Program for Computer Assisted Stereotaxic Surgery,xe2x80x9d Proceedings of the Fifth Annual Symposium on Computer Applications in Medical Care, Nov. 1981; Galloway, R. L., Jr., xe2x80x9cOrientation and Registration of Three-Dimensional Images,xe2x80x9d Textbook of Stereotactic and Functional Neurosurgery (1997); Galloway, R. L., Jr., xe2x80x9cFrameless Stereotactic Systems,xe2x80x9d Textbook of Stereotactic and Functional Neurosurgery (1997); Parkinson, A. R., et al., xe2x80x9cOPTDES.BYU: A Software System for Optimal Engineering Design,xe2x80x9d Proceedings of ASME International Computers in Engineering Conf., Las Vegas, Nev., August 1984); Parkinson, A. R., et al., xe2x80x9cConsideration of Worst-Case Manufacturing Tolerances in Design Optimization,xe2x80x9d Transactions of the ASME, Vol. 108, December 1986. Advertising Literature providing additional background includes: Reusable/Disposable Frame Head Immobilizer, BIONIX Co. (April 1996); Pelvis/Belly Board Immobilizer, BIONIX Co. (April 1996); 3-D Pelvis Board Immobilizer, BIONIX Co. (April 1996); HipFix Hip and Pelvic Immobilization System, MED-TEC Inc. (1995); Vac-Lok Patient Immobilization System, MED-TEC, Inc. (1996); Redi-Foam Foam Immobilization System, MED-TEC, Inc. (1996); Stereotactic Body Frame Dose escalation by precision conformal radiotherapy, Precision Therapy International (September 1995); Extracranial Radiosurgery, Leibinger (1997); Uni-Frame Head Immobilization System, MED-TEC, Inc. (1996); Alpha Cradle brand Patient Repositioning Systems, Smithers Medical Products, Inc. (1995); IZI Medical Products Corp. World Wide Web Home Page (September 1999); Biosense Magellan Image-Guidance for Brain, Spine, and Sinus Surgery (date unknown); and Computerized Imaging Reference Systems, Inc., 3D Skull Phantom (November 1999).
The present invention is of a system for use in the field of medicine and primarily for fractionated stereotactic radiotherapy/radiosurgery and other stereotactic procedures. The system is an external whole body immobilization and stereotactic localizer system. The term xe2x80x98whole bodyxe2x80x99 refers to all or some portion of the body of the patient. The term xe2x80x98stereotactic localization systemxe2x80x99 as used in the art of stereotactic treatment particularly of the patient""s brain, generally includes some means for immobilizing the patient""s cranium and is thus part of the xe2x80x98stereotactic localization systemxe2x80x99; however, in this application the term xe2x80x98whole body immobilizationxe2x80x99 system is used as a complement to the xe2x80x98stereotactic localization system;xe2x80x99 the two systems comprise the present invention. It gives a high degree of precision target localization for whole body stereotactic procedures including biopsy and radiotherapy with a unique imaging resolver fiducial localization method. As noted above, the need for effective patient immobilization has become widely recognized in recent years, particularly as the application of conformal radiation treatment techniques (where small treatment margins are possible) has increased. (Bentel, 1999 pp. 23-38). Stereotactic conformal radiotherapy with dose escalation to the targeted lesion is improved with this accurate and reproducible target localization system. Head, neck, thoracic, abdominal, or pelvic localization is possible with the present invention, which may be extended to include the entire body.
The present invention is of a body immobilization and stereotactic localization frame and method comprising use of a non-invasive device for immobilizing a human body from head to pelvis comprising form fitting custom molds for both anterior and posterior portions of the body. In the preferred embodiment, the posterior mold is a vacuum mold or polyurethane foam mold and the anterior mold is a thermoplastic mold, both being reusable over the course of a fractionation or other treatment regimen for the subject patient. The frame comprises two or more imaging localization fiducials each having a repetitive trigonometric waveform wherein one of the two fiducials is offset along the longitudinal axis of the frame relative to the position of a second of the fiducials. The two or more imaging localization fiducials additionally include quality assurance fiducials placed in opposing pairs at predetermined laterally spaced positions parallel to the longitudinal axis of the frame. The word xe2x80x9cfiducialxe2x80x9d means xe2x80x9cdesignating a line, point, etc. assumed as a fixed basis of comparisonxe2x80x9d. 1 New Shorter Oxford English Dictionary, 942 (Clarendon Press, Oxford England) (1993 Ed.). A fiducial is made from a material (as defined below) that appears in an image as a marker to indicate its location used in the determination of the image stereotactic coordinates.
The present invention is also of a stereotactic localization frame and method employing an imaging resolver (as subsequently defined) comprising a continuous array of coupled fiducials. In the preferred embodiment, two or more imaging localization fiducials have a repetitive waveform , preferably a trigonometric wave form such as a sine or cosine waveform, and most preferably the two fiducials are longitudinally offset by a xcfx80/2 distance. A non-invasive device for immobilizing a human body from head to pelvis is employed comprising form fitting custom molds for both anterior and posterior portions of the body.
The present invention is further a radiation treatment regimen comprising: using a stereotactic body frame with imaging resolver; forming posterior and anterior body molds of a patient for use in the frame; aligning the frame in an imaging gantry; taking images of the patient; transporting the images to computer treatment planning system; calibrating the images; performing volumetric determinations; determining stereotactic position of one or more volumes within the body; composing a radiation treatment plan to effectively treat one or more volumes within the body; aligning the patient, body molds, and frame in a radiation treatment facility; and treating the patient according to the plan. In the preferred embodiment the aligning and treating steps may be repeated for the same patient one or more additional times and other stereotactic treatment plans may be performed.
The system of the invention was developed to meet the fundamental requirements of body immobilization and stereotactic localization in a non-invasive manner. In addition, the invention is capable of immobilizing the head and neck as well as the thoracic, abdomen, and pelvis. Its fiducial localizer system is continuous from head to pelvis and allows accurate and continuous stereotactic imaging and localization throughout the entire upper body and by simple extensions it can be used for localization of the entire body. The advantages of the invention are increased accuracy, reliability, and whole body localization. Immobilization is achieved by the use of a vacuum mold system or polyurethane foam mold for posterior (the part of the body nearest the frame base) areas and a thermoplastic body mold to cover large body surfaces in the ventral or anterior plane. The method of combined anterior and posterior form fitting custom molded immobilization, which cover wide surface areas of the body, improves immobilization and repositioning as well as minimizing diaphragmatic and abdominal movements. The vacuum or foam molds and the thermoplastic molds can be stored and reused for each patient in a radiation fractionation or other treatment regimen. All components of the invention, including the visible frame coordinates and scales, provide for precise target treatment.
The localization features of most stereotactic frames are similar, differing mainly in the organization of the coordinate system of the frame and its mechanical dimensions. All stereotactic frames are created for the purpose of immobilization, precise patient repositioning, and localization of volume structures or lesions within the volumetric space defined by the frame and the immobilized body part. With regards to stereotactic frames, the general convention is that the long axis of the body (longitudinal axis) is given the designation of the z-axis in the Cartesian coordinate system of three-dimensional spatial localization. The left-right transverse axis is generally designated as the x-axis and the anterior/posterior (vertical) axis is designated as the y-axis. Most conventional stereotactic frames use incremental indicators in millimeters and centimeters along each axis for precise coordinate referencing. The aim of the stereotactic frame system of the present invention is to permit a wide area of body immobilization and allow precise stereotactic imaging and positioning of body areas within the frame.
The word xe2x80x9cwaveformxe2x80x9d is used to refer to a xe2x80x9cwave regarded as characterized by a particular shape or manner of variation. esp. a varying voltage,xe2x80x9d 2. The New Shorter Oxford English Dictionary, 3638 (Clarendon Press, Oxford, England) (1993 Ed.), and refers to one period or phase length. A xe2x80x9crepetitive waveformxe2x80x9d, refers to a repeating series of the waveform.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.